Variations in cellular attenuation and vesicle numerical densities in capillary endothelium and type I epithelium of isolated, perfused dog lungs after acute severe edema formation.

Morphometric comparisons of nonedematous and edematous isolated, perfused dog lungs establish that there are significant differences between the degree of cellular attenuation and vesicle numerical densities in endothelial and type I epithelial cells of the alveolar septa after edema production. In nonedematous isolated lungs the extent of endothelial and epithelial attenuation was greater on the thin sides of the septa. In the edematous lungs, the differential of greater thin-side attenuation was maintained for the endothelium but not for the epithelium where the extent of attenuation in the septal thick segments was increased. Vesicle numerical densities were approximately doubled in the cells on both sides of the septa in the edematous lungs. The endothelial vesicle densities were greater in the septal thin segments than in the septal thick segments in both the nonedematous and the edematous isolated lungs. The epithelial vesicle densities, on the other hand, were similar on the thin and thick sides of the septa in the nonedematous and edematous lung preparations. Although the contribution of vesicles to cellular function in the alveolar septa remains uncertain, further evaluation of vesicular transport should include the possible variability of this function with the varying degrees of cellular attenuation on the two anatomically distinct sides of the septa.